The present invention generally pertains to television signal processing and is particularly directed to regeneration of a color burst signal.
In order to conserve transmission bandwidth, it may be desirable to transmit a less-than-standard-length color burst information signal with a video information signal in lieu of a standard-length color burst signal. For example, when transmitting a scrambled television signal, an original standard-format video signal, as shown in FIG. 1A, containing a sinusoidal color burst signal 10 preceding the video information 12 in each horizontal line is converted into a format, such as shown in FIG. 1B, wherein a color burst information signal 14 of less than standard length, but phase coincident with the color burst signal 10 in the original video signal (FIG. 1A) is positioned between segments of audio and/or control information 16 and video information 18. Typically the less-than-standard length color burst information signal 14 in the converted signal is formed by truncating the color burst signal 10 in the original video signal and thus has the same frequency and phase as the standard-length color burst signal in the original video signal.
The present invention provides a system for regenerating a standard-length color burst signal from a less-than-standard-length color burst information signal of a given frequency and phase. The system of the present invention includes means for generating a system clock signal from the color burst information signal, with the clock signal having a clock frequency related to and at least twice the given frequency of the color burst information signal; means for sampling and storing phase information from the color burst information signal, wherein said sampling is clocked by the system clock signal; and means for regenerating a standard-length color burst signal at the given frequency and in phase with the color burst information signal by retrieving and extrapolating the stored phase information, wherein said retrieval is clocked by the system clock signal.
Additional features of the present invention are described with reference to the description of the preferred embodiment.